Embodiments of the inventive concept relate generally to nonvolatile memory systems. More particularly, embodiments of the inventive concept relate to nonvolatile memory systems capable of preventing data loss in the presence of power interruption.
Semiconductor memory devices can be roughly classified into two categories including volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power. Examples of volatile memory devices include dynamic random access memory (DRAM) and static random access memory (SRAM), and examples of nonvolatile memory devices include electrically erasable and programmable read-only memory (EEPROM), ferroelectric random access memory (FRAM), phase-change random access memory (PRAM), magnetic random access memory (MRAM), and flash memory.
Among the nonvolatile memory devices, flash memory is known for having relatively high program speed, low power consumption, and large storage capacity. Accordingly, flash memory devices have been adopted as data storage media in a wide variety of electronic devices, such as MP3 players, digital cameras, solid state drives (SSDs) and computer systems, to name but a few.
Nonvolatile memories such as flash memory are commonly incorporated into nonvolatile memory systems, such as SSDs, to provide mass data storage for various electronic applications. A nonvolatile memory system typically receives power from an external or internal power supply, such as a 110V or 220V AC power supply, or a DC power supply such as a battery.
Unfortunately, power supplies are susceptible to failures, which can lead to loss of data even in nonvolatile memory devices. For instance, if the power supply of a nonvolatile memory device is unexpectedly interrupted during a programming operation, some memory cells in the nonvolatile memory device may be left in an unknown state, which can potentially lead to catastrophic system malfunctions.